title: A comparison between two powder compaction parameters of plasticity: the effective medium A parameter and the Heckel 1/K parameter.
abstract: The purpose of the research was to introduce a procedure to derive a powder compression parameter (EM A) representing particle yield stress using an effective medium equation and to compare the EM A parameter with the Heckel compression parameter (1/K). 16 pharmaceutical powders, including drugs and excipients, were compressed in a materials testing instrument and powder compression profiles were derived using the EM and Heckel equations. The compression profiles thus obtained could be sub-divided into regions among which one region was approximately linear and from this region, the compression parameters EM A and 1/K were calculated. A linear relationship between the EM A parameter and the 1/K parameter was obtained with a strong correlation. The slope of the plot was close to 1 (0.84) and the intercept of the plot was small in comparison to the range of parameter values obtained. The relationship between the theoretical EM A parameter and the 1/K parameter supports the interpretation of the empirical Heckel parameter as being a measure of yield stress. It is concluded that the combination of Heckel and EM equations represents a suitable procedure to derive a value of particle plasticity from powder compression data.
authors.affiliation: Department of Pharmacy, Uppsala University, Uppsala Biomedical Center, P.O. Box 580, SE-751 23 Uppsala, Sweden.
authors.forename: Foad
authors.initials: F
authors.lastname: Mahmoodi
authors.forename: Ingvild
authors.initials: I
authors.lastname: Klevan
authors.forename: Josefina
authors.initials: J
authors.lastname: Nordström
authors.forename: Göran
authors.initials: G
authors.lastname: Alderborn
authors.forename: Göran
authors.initials: G
authors.lastname: Frenning
mesh_terms: D000465:Algorithms; D019245:Compressive Strength; D004339:Drug Compounding; D005079:Excipients / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000737:chemistry; D011208:Powders / Q000737:chemistry*
chemical_list: D005079:Excipients; D004364:Pharmaceutical Preparations; D011208:Powders
keywords: Compression parameter; Effective medium equation; Heckel equation; Powder compression; Yield stress